Conditions for Setting the DTC: P0961
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
The TCM detects an internal electrical performance malfunction of the line PC solenoid control circuit and the actual line pressure does not equal the commanded line pressure for 300 milliseconds.